Use golang-builder base image for tests in CircleCI

Use promu default go version + use 1.6 tag for cicleci tests

Skip metrics with invalid utf8

Tolerate more forms of broken lines from StatsD

* Don't panic on empty metric names
* Don't panic on empty metric components
* Test tolerance the above kinds of broken StatsD lines

Release 0.3.0

Fix CircleCI flanky go get

Use common/version and common/log packages

New build process

Vendor dependencies

Drop _count suffix for loaded_mappings metric 

This makes the naming consistent with our best pratices.

Make metric suffixes optional, expose unmapped events

Dogstats extensions squashed

 - add tests for edge cases
 - fix typo

Increase receivable UDP datagram size to 65535 bytes.

Fixes https://github.com/prometheus/statsd_exporter/issues/35

Don't panic when negative number counter is submitted.

Instead now we will send a warning message to the logs
and continue on with our day.

Also a guard has been added when we detect a channel has been
closed and the `Exporter.Listen` function will return out of
its loop vs always running. When a channel is closed there will
be no more data to consume, so this seems correct. It also allows
for a test to be written for the panic.